A brush chipper such as described in my German patent document No. 2,934,792 has a housing formed with an upwardly open funnel-shaped inlet hopper centered on a vertical axis and opening downwardly into a chipping or comminution chamber into which a lateral inclined intake also opens. This housing is provided with a shaft supported on bearings and provided at its lower end with a V-belt pulley connected by a belt to a pulley on the output shaft of a drive motor so that this shaft can be rotated by the motor about its axis.
A nut secures a blade-support plate to the upper end of this shaft, with the plate perpendicular to the axis. in addition this nut bolts a plate having a plurality of upwardly extending arms to the upper side of this support plate. These arms lie above baffles fixed in the comminution chamber. The blade plate is provided with blades bolted in place behind, relative to the normal rotation direction of the blade plate, radially outwardly open slots formed by bending down of tabs.
Brush to be chipped is fed into either of the intakes. The brush entering via the intake funnel is broken up by the arms coacting with the baffles and then, like the brush or sticks entering via the lateral intake, is chopped up by the blades to pass through the wheel at the slots ahead of the blades. Thence the chips pass radially out of the machine through a radially outwardly open discharge to be deflected downwardly by a plate into an appropriate receptacle.
These blades are normally rectangular with two opposite long sides ground to straight cutting edges. Two screws secure each blade in place behind the respective slot, with the cutting edge extending radially of the axis. Such a blade can be taken off and turned over to use its second edge when the first becomes dull. As a rule the blades to dull rather rapidly, since in addition to cutting wood, they inevitably encounter dirt, small stones, and even an occasional nail or other metal object. Hence the blades must be flipped and/or replaced fairly frequently.
Whether the blade is simply being turned over to use its other edge, or replaced with a new blade, it is necessary to fully withdraw the two screws and reinsert them once the blade has been repositioned or a new blade has been put in. Such a job is fairly onerous, and the occasional screw is dropped into and lost in the mechanism of the machine, further complicating matters.